Liquid Metal Encased in Biomimic Polydopamine Armor to Reinforce Photothermal Conversion and Photothermal Stability

Abstract Liquid metal (LM) faces numerous obstacles like spontaneous coalescence, prone oxidizability, and deterioration in photothermal conversion, impeding the potential application as photothermal agent. To tackle these issues, several studies have focused on surface engineering strategy. Developing a feasible and efficient surface engineering strategy is crucial to prevent the aggregation and coalescence of LM, while also ensuring exceptional photothermal conversion and biosecurity. In order to achieve these goals in this work, the biomimetic polydopamine (PDA) armor was chosen to encase a typical LM (eutectic gallium‐indium‐tin alloy) via self‐polymerization. Characterization results showed that the PDA encased LM nanoparticle exhibited enhanced photothermal stability, photothermal conversion, and biosecurity, which could be derived from the following factors: (1) The PDA protective shell acted as an “armor”, isolating LM from dissolved oxygen and water, inhibiting heating‐accelerated oxidation and shape morphing. (2) The exceptional near‐infrared absorption of PDA was conducive to the photothermal conversion. (3) The biomimetic characteristic of polydopamine (PDA) was advantageous for improving the biosecurity. Hence, this work presented a new surface engineering strategy to reinforce LM for photothermal conversion application.